In recent years, a device has been widespread which digitally treats image information and which, in order to transmit and accumulate the information with high efficiency in this case, performs compression encoding of an image by adopting an encoding method in which compression is performed by orthogonal transform, such as a discrete cosine transform, and motion compensation using the redundancy unique to image information. Examples of the encoding method include an MPEG (Moving Picture Experts Group) or H.264 and MPEG-4 Part10 (Advanced Video Coding; hereinafter, referred to as H. 264/AVC) and the like.
In addition, currently, in order to further improve the encoding efficiency than H.264/AVC, standardization of an encoding method called HEVC (High Efficiency Video Coding) has been developed by JCTVC (Joint Collaboration Team-Video Coding) that is a joint standardization group of ITU-T and ISO/IEC. For the HEVC standard, Committee draft that is a first draft specification has been issued in February, 2012 (for example, refer to Non-patent Document 1).
In the draft of the HEVC at present, a deblocking filter, an adaptive loop filter, and an adaptive offset filter are adopted as in-loop filters, and there are two parameters of a deblocking filter including a parameter β and a parameter Tc. The parameter β has 52 values of 0 to 51, and is fixed to 64 for an input larger than 51. The parameter Tc has 54 values of 0 to 53, and is fixed to 13 for an input larger than 53.
The range of a quantization parameter QP that can be used in the HEVC is 0 to 51, but the range of the offset of the parameter of the deblocking filter is −26 to 26. Therefore, theoretically, the input range of the LUT (Look Up Table) of the parameter of the deblocking filter is 0 to 77.